The present invention relates to the design and construction of high performance shock absorbers. More particularly, the present invention relates to a light-weight, adjustable twin tube shock absorber comprising an air-assisted, coil sprung suspension system that is hydraulically damped. The suspension system of the present invention is particularly suited for use in connection with a bicycle suspension system such as a rear bicycle wheel suspension assembly.
In the past, suspension systems in general have been used for many applications, including cushioning impacts, vibrations or other disturbances experienced by vehicles and machinery. Typical vehicles benefitting from the use of suspension systems include bicycles and motor-cycles. For example, bicycles have been developed with suspension systems for cushioning impacts or vibrations incurred when the bicycle is ridden over bumps, ruts, rocks, pot holes, or other obstacles. Typically, bicycle suspension systems have been configured for use in the front or rear bicycle fork, in the head tube that connects the front fork to the bicycle frame and handlebars, in the seat post, and in conjunction with a rear wheel swing-arm assembly, as well as in other locations.
Shock absorbers are commonly used with suspension systems to damp undesirable oscillations of the suspension system caused by irregularities of the road surface. A commonly used shock absorber is a hydraulic type which uses a piston and cylinder arrangement. Damping fluid in the cylinder is forced by the piston (which moves with the functioning of the suspension system) through narrow holes or valves. The resistance encountered as the fluid passes through the holes or valves damps the oscillations of the suspension system.
There is an ongoing need for improvements in the art of shock absorbers. For example, there is a need in shock absorbers, particularly those used in bicycle suspension applications, for reductions in weight and manufacturing costs. There is also a need for a high degree of adjustability of the damping capabilities and characteristics of shock absorbers. In particular, there is a need for a shock absorber in which the main compression spring used for supporting a load applied to the suspension system has a broad range of adjustability for adapting to a wide variety of load conditions. In addition, it is desirable to have a shock absorber with a high degree of compression and rebound damping adjustment capability, and particularly for such a shock absorber in which the compression and rebound damping characteristics are separately adjustable. Finally, there is a need for improvements of the kind previously described which result in a more rigid shock design.
It is therefore an object of the present invention to provide a shock absorber that permits a high degree of main compression spring adjustability.
It is another object of the present invention to provide a shock absorber having a damping system permitting a high degree of damping adjustability.
It is yet another object and to provide a shock absorber in which the compression and rebound damping characteristics are separately adjustable.
It is another object to provide a rigid shock absorber having low weight and manufacturing costs.